The thermoelectric effect refers to a reversible and direct energy conversion between heat and electricity. The thermoelectric effect is generated by transfer of charge carriers, that is, electrons and holes in materials.
The Seebeck effect is a conversion of temperature differences directly into electricity, and has been applied to the field of power generation using an electromotive force generated due to a difference in temperature between both ends of a thermoelectric material. The Peltier effect is an effect in which heat is produced at an upper junction and absorbed at a lower junction when an electric current is allowed to flow in a circuit, and has been applied to the field of cooling systems using a difference in temperature between both ends of a thermoelectric material caused by an electric current applied from the outside. Meanwhile, the Seebeck effect and the Peltier effect differ from Joule heating in that these effects are thermodynamically reversible but Joule heating is not thermodynamically reversible.
In recent years, thermoelectric materials have been applied to passive cooling systems for semiconductor equipment and other electronic devices in which it is difficult to solve problems regarding production of heat in active cooling systems, and demand therefor has been expanded to fields in which the problems were not solved in the systems using a conventional refrigerant gas compression method, that is, precision temperature control systems applied to DNA studies. Thermoelectric cooling is an environmentally friendly cooling technique which causes neither vibration nor noise and in which no refrigerant gases causing environmental issues are used. When cooling efficiency is improved with the development of high-efficiency thermoelectric cooling materials, such thermoelectric cooling materials will expand to application fields of general cooling systems such as commercial and household refrigerators, air conditioners, etc. In addition, when a thermoelectric material is applied to automotive engine units, facilities from which a large amount of heat is released in industrial factories, etc., electricity may be generated due to difference in temperature caused between both ends of the thermoelectric material. As a result, the thermoelectric material has drawn attention as one new and renewable energy source.